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1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

Code 118 continuity test 95 150, 351w

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Old Mar 23, 2023 | 06:58 PM
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Code 118 continuity test 95 150, 351w

Alright, i think im about to sound crazy here,

i ran a continuity test from the solid grey ECT sensor wire (not sig return wire) to the PCM on pin 7.
came up with nothing.

i disconnected the harness near the fuse box to see if the break was before or after that connection, or the whole wire.

i found good continuity to the 4th pin from the bottom to the ECT (picture included) but no continuity to where that pin SHOULD meet on the other connector to pin 7 on the PCM



. But i did get continuity to pin 25 (IAT) to where the ECT should connect in. Kind of confused here.. its like the pins are offset by one, and i checked it 3 separate times to make sure i wasnt going crazy.

does the IAT share the same pin, or somehow connected with each other? Do i need to replace that 4th wire On the connector to the PCM?
 
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Old Mar 24, 2023 | 07:48 AM
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If you look closely on the back side of the connectors, you can see raised numbers of the pins at the end of each row.

Makes it easier to count over, plus, verify color code of wire for pin you're looking for.

IAT & ECT are definitely separate inputs to ECU.

By any chance does your truck have a updated ECT replacement sensor that's square vs original round?
 
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Old Mar 24, 2023 | 08:07 AM
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ECT signal is a Light Green/Red wire that goes to PCM Pin 7. The IAT/ACT sensor output is the Gray wire that goes to PCM Pin 25.
 
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Old Mar 24, 2023 | 08:41 AM
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Randy, diagram is great, but...

IAT (manifold mount) return per right diagram on a 5.8 should go through connector 101 as does & is shown for ECT left shouldn't it?

On MAF 5.0 IAT (air box mount) return is straight shot to ECU.

Can you explain discrepancy or what am I missing & maybe what OP is dealing with?
 
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Old Mar 24, 2023 | 09:29 AM
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David, good catch. I verified I was using a non-California emission 1995 5.8L engine diagram for the ECT and IAT circuits. Looks like Ford did mix in the MAF version details of the 5.8L engine without labeling it as such. Either that or neglected to include the C101 connections for the IAT circuit.You are correct non-MAF trucks for both the ECT and IAT circuits do go through C101. ECT signal is C101 Pin 5 (Light Green/Red) and IAT is C101 Pin 6 (Gray).

ECT Circuit number is 354 (Pin 5). IAT Circuit number is 743 (Pin 6).

C101 Pin-out for a 1995 F-Series/Bronco:
 
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Old Mar 24, 2023 | 09:56 AM
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I wouldn't have noticed but for upgrading a 5.8 harness to MAF & 101 is where he's having problems.
 
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Old Mar 26, 2023 | 02:10 PM
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Originally Posted by Scndsin
If you look closely on the back side of the connectors, you can see raised numbers of the pins at the end of each row.

Makes it easier to count over, plus, verify color code of wire for pin you're looking for.

IAT & ECT are definitely separate inputs to ECU.

By any chance does your truck have a updated ECT replacement sensor that's square vs original round?
Sorry for the long reply, number 5 and 6 are swapped on c101M based off of continuity tests between sensors and pins, grey leads all the way to the ECT and green leads to the IAT. Weird. C101F is correct to the PCM. Anyone got a video or link on how to swap those pins?
 
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Old Mar 26, 2023 | 05:08 PM
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"I" doit with a large safety pin.

After working the silicon plug out of the back so I can grab the exact wire to the pin/plug firmly...

Use the SP to work the wedge lock out of the center of the front.

The red main pin/plug lock can be pulled out. I use hemostats.

You're then left with the pin/plug retainers.

Long fragile plastic finger with a wedge in its middle (fits in hole of pin or plug) that stays with the connector housing & retains the metal pin/plug and breaks easily.

The idea is to pull the finger back with the SP enough to let the wedge clear the hole in the pin/plug & push the wire & pin/plug up just (sometimes pulls straight out, sometimes needs movement first) a bit to confirm release & then pull straight out the back.

If you don't break the finger, when you re-insert the pin/plug back in, it just snaps in place.

The Trick Is:

The very end of the finger is angle cut, so the Safety Pin point has to be very sharp to get under the tip of the finger or otherwise the point just skips off the tip of the finger rather than under it.

They make tools for this. I can't get them to work for me.

Sorry, I've lost my pics showing 90% of this.

Infinite patience is a virtue.
 
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